My Colt 6920CA M4. Obvious not total clone because I cant use the shorter barrel like the military version but anyways. I love it. I swapped a regular Colt M4 butt stock onto it, knights armament rail system, surefire light and also have the ACOG which I just sighted in this past weekend for this weapon. I had the TA31 when I had one but the TA01 I like better for the finer crosshairs at the range.